Warmer Than Normal Start to August

Warmer Than Normal Start to August:

The first 7 days of August have brought warmer than normal temperatures to most parts of the state, with mean daily temperatures averaging 3-5 degrees F above normal. For many, August 8th brought the first cooler than normal day of the month, with low relative humidity and dew points. August 9th continued that pattern as well. So far the highest temperature in the state this month has been 94°F at St James (Watonwan County) on the 4th, and many places up north have seen lows in the 40s F.

Widely scattered thunderstorms have produced a large range in rainfall so far this month, with some areas receiving 1-2 inches, and many reporting less than half an inch. Earlier this week on August 6th many observers in southeastern Minnesota reported over 1 inch of rainfall, while Spring Valley, Hokah, Grand Meadow, and Waseca reported over 2 inches. Rochester and Owatonna both report over 36 inches of precipitation so far in 2019, already ranking among their 20 wettest years in history, and still over 5.5 months to complete the year.

Weekly Weather Potpourri:

Large hail and strong winds crossed Minnesota on August 5th (Monday). Some areas reported winds over 60 mph, and there were many reports of large hail, including baseball-size stones, and near Delano, grapefruit sized (4 inches). You can read more about this from the Minnesota State Climatology Office web site.

The Minnesota Extreme Heat Toolkit developed by the Minnesota Department of Health is featured in an article from NOAA this week. It showcases how communities can better plan for coping with health risks that are associated with high Heat Index values.

In this week’s AGU-EOS bulletin there is an interesting article that highlights the recent massive loss of ice from Greenland. The Greenland ice sheet broke records on 1 August 2019 by losing more water volume in 1 day than on than any other day since records began in 1950, shedding 12.5 billion tons of water into the sea. Temperatures so far in August are running up to 10°F above normal, following above normal temperatures in April, May, June, and July as well.

In the Western Pacific Ocean Typhoon Lekima developed and was moving southeast of Tawan with winds over 110 mph and sea wave heights of 30 feet. It was expected to weaken as it nears the coast of China this weekend. Elsewhere in the Western Pacific Ocean Typoon Krosa was southeast of Japan with wind speeds up to 105mph and sea wave heights of 32 feet. It was expected to weaken significantly before approaching the coast of Japan early next week.

MPR listener question

I am curious how this summer compares to past summers with respect to overall (or perhaps average) moisture levels in the atmosphere. It seems that 6 out 7 days each week has been very muggy, even when temperatures are near normal.

Answer:

The common measures for atmospheric moisture levels are relative humidity and dew point. Examining those measurements for this summer shows that they were below average in general for the month of June, and so far for the month of August. Conversely, they were well above average during the month of July. Humidity levels were above 70 percent in the Twin Cities Metro Area during July more than any year since 2004, and uncomfortable dew points of 65°F or greater were 30 percent above average during July as well. This at least partially explains why we recorded 8 nights when the low temperature never fell below 70°F.

Twin Cities Almanac for August 9th:

The average MSP high temperature for this date is 82 degrees F (plus or minus 7 degrees F standard deviation), while the average low is 63 degrees F (plus or minus 6 degrees F standard deviation).

MSP Local Records for August 9th:

MSP weather records for this date include: highest daily maximum temperature of 95 degrees F in 2010; lowest daily maximum temperature of 60 degrees F in 1994; lowest daily minimum temperature is 46 degrees F in 1972; highest daily minimum temperature of 76 degrees F in 2010; record precipitation of 3.34 inches in 1914; and no snow has fallen on this date.

Average dew point for August 9th is 59 degrees F, with a maximum of 79 degrees F in 1992 and a minimum of 37 degrees F in 1927.

All-time state records for August 9th:

The state record high temperature for this date is 104 degrees F at Canby (Yellow Medicine County) in 1947. The state record low temperature for this date is 28 degrees F at Tower (St Louis County) in 1994. State record precipitation for this date is 5.25 inches at Two Harbors (Lake County) in 1939: and no snowfall has occurred on this date.

Past Weather Features:

August 9, 1947 brought extreme temperature variation to Minnesota. Most of the state saw temperatures climb into the 90s F, with 7 communities in southwestern counties recorded afternoon highs of 100°F or greater. Northeastern Minnesota along Lake Superior was enjoying a breeze off the lake, with afternoon highs ranging from 61 to 67 degrees F.

Strong thunderstorms over August 9-10, 1948 brought heavy rains and flash flooding to many parts of southern and central Minnesota. Many communities reported 4 to 7 inches of rainfall, while Mankato, Winthrop, and Faribault reported over 7 inches.

Campers in northern Minnesota on August 9, 1994 awoke to chilly morning temperatures ranging from 28°F to 35°F in St Louis, Lake, and Koochiching Counties. Afternoon high temperatures did climb into the 60s F.

Outlook:

Increasing cloudiness on Saturday with a chance for showers and thunderstorms and cooler than normal temperatures. Then drier on Sunday. Another chance for showers and thunderstorms later on Monday and Tuesday. Temperatures will generally be a few degrees cooler than normal, then warming up towards the end of next week to near normal with increased chances for scattered showers and thunderstorms.